Positioning location for remote radio heads (rrh) with same physical cell identity (pci)

ABSTRACT

A method of wireless communication includes generating a unique position reference signal (PRS) for a remote radio head having a same physical cell identity (PCI) as a macro eNodeB. The unique PRS is based on a virtual cell ID and/or unique cell global identification (CGI) of the remote radio head such that the unique PRS is different from a PRS of the macro eNodeB. The PRS of the macro eNodeB is based on the PCI. The method also includes transmitting the unique PRS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/401,696, entitled “POSITIONING LOCATION FOR REMOTE RADIO HEADS (RRH)WITH SAME PHYSICAL CELL IDENTITY (PCI),” filed on Feb. 21, 2012, whichclaims the benefit under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication No. 61/445,489 entitled “POSITIONING LOCATION FOR REMOTERADIO HEADS (RRH) WITH SAME PCI,” filed on Feb. 22, 2011, thedisclosures of which are expressly incorporated by reference herein intheir entireties.

BACKGROUND

1. Field

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly to configuring remote radioheads.

2. Background

Wireless communication networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, etc. These wireless networks may be multiple-access networkscapable of supporting multiple users by sharing the available networkresources. A wireless communication network may include a number of basestations that can support communication for a number of user equipments(UEs). A UE may communicate with a base station via the downlink anduplink. The downlink (or forward link) refers to the communication linkfrom the base station to the UE, and the uplink (or reverse link) refersto the communication link from the UE to the base station.

A base station may transmit data and control information on the downlinkto a UE and/or may receive data and control information on the uplinkfrom the UE. On the downlink, a transmission from the base station mayencounter interference due to transmissions from neighbor base stationsor from other wireless radio frequency (RF) transmitters. On the uplink,a transmission from the UE may encounter interference from uplinktransmissions of other UEs communicating with the neighbor base stationsor from other wireless RF transmitters. This interference may degradeperformance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, thepossibilities of interference and congested networks grows with more UEsaccessing the long-range wireless communication networks and moreshort-range wireless systems being deployed in communities. Research anddevelopment continue to advance the UMTS technologies not only to meetthe growing demand for mobile broadband access, but to advance andenhance the user experience with mobile communications.

SUMMARY

One aspect discloses a method of wireless communication. The methodincludes configuring a plurality of remote radio heads (RRHs) where eachRRH has the same physical cell identity (PCI) as a macro eNodeB. TheRRHs are configured to prevent position location reference signal (PRS)transmissions on subframes where a macro eNodeB transmits PRS. Themethod also includes communicating in accordance with the configuration.

In another aspect, a method of wireless communication disclosesconfiguring a plurality of remote radio heads (RRHs). Uplinktransmissions are received from a user equipment (UE) and the positionlocation of the UE is determined based on received signal timedifference (RSTD) measurements of the received uplink transmissions atthe RRHs and macro eNodeB.

In another aspect, the method of wireless communication disclosesgenerating a unique position location reference signal (PRS) for aremote radio head. The PRS is generated based a virtual cell ID and/orunique cell global identification (CGI) of the remote radio head. Theunique position location reference signal is then transmitted.

Another aspect discloses a wireless communication having a memory and atleast one processor coupled to the memory. The processor(s) isconfigures a plurality of remote radio heads (RRHs), where each RRH hasa same physical cell identity (PCI) as a macro eNodeB. The RRHs areconfigured to prevent position location reference signal (PRS)transmissions on subframes where a macro eNodeB transmits PRS. Theprocessor is configured to communicate in accordance with the RRHconfigurations.

In another aspect, the wireless communication discloses a processor(s)configuring a plurality of remote radio heads (RRHs). The processor(s)is also configured to receive uplink transmissions from a user equipment(UE). The processor(s) is also configured to determine a positionlocation of the UE based on received signal time difference (RSTD)measurements of the received uplink transmissions at the RRHs and macroeNodeB.

In another aspect, the wireless communication discloses a processor(s)configured to generate a unique position location reference signal (PRS)for a remote radio head (RRH). The unique PRS is based on a virtual cellID and/or a unique cell global identification (CGI) of the remote radiohead. The processor is also configured to transmit the unique positionlocation reference signal.

Another aspect discloses a computer program product for wirelesscommunications in a wireless network having a non-transitorycomputer-readable medium is disclosed. The computer-readable medium hasnon-transitory program code recorded thereon which, when executed by theprocessor(s), causes the processor(s) to perform operations ofconfiguring a plurality of remote radio heads (RRHs), where each RRH hasa same physical cell identity (PCI) as a macro eNodeB, to preventposition location reference signal (PRS) transmissions on subframeswhere a macro eNodeB transmits PRS. The program code also causes theprocessor(s) to communicate in accordance with the configuration.

In another aspect, the computer program product for wirelesscommunications discloses a computer-readable medium, when executed bythe processor(s), causes the processor(s) to configure a plurality ofremote radio heads (RRHs) and to receive uplink transmissions from auser equipment (UE). The program code also causes the processor(s) todetermine a position location of the UE based on received signal timedifference (RSTD) measurements of the received uplink transmissions atthe RRHs and macro eNodeB.

In another aspect, the computer program product for wirelesscommunications discloses a computer-readable medium, when executed bythe processor(s), causes the processor(s) to generate a unique positionlocation reference signal (PRS) for a remote radio head based on avirtual cell ID and/or unique cell global identification (CGI) of theremote radio head. The program code also causes the processor(s) totransmit the unique position location reference signal.

Another aspect discloses an apparatus for wireless communication andincludes means for configuring a plurality of remote radio heads (RRHs)to prevent position location reference signal (PRS) transmissions onsubframes where a macro eNodeB transmits PRS. Each of the RRHs have asame physical cell identity (PCI) as a macro eNodeB. Also included ismeans for communicating in accordance with the configuration.

In another aspect, the apparatus discloses means for configuring aplurality of remote radio heads (RRHs) and means for receiving uplinktransmissions from a user equipment (UE). Also included is means fordetermining a position location of the UE based on received signal timedifference (RSTD) measurements of the received uplink transmissions atthe RRHs and macro eNodeB.

In another aspect, the apparatus discloses means for generating a uniqueposition location reference signal (PRS) for a remote radio head basedon a virtual cell ID and/or unique cell global identification (CGI) ofthe remote radio head. Also included is means for transmitting theunique position location reference signal.

This has outlined, rather broadly, the features and technical advantagesof the present disclosure in order that the detailed description thatfollows may be better understood. Additional features and advantages ofthe disclosure will be described below. It should be appreciated bythose skilled in the art that this disclosure may be readily utilized asa basis for modifying or designing other structures for carrying out thesame purposes of the present disclosure. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the teachings of the disclosure as set forth in the appendedclaims. The novel features, which are believed to be characteristic ofthe disclosure, both as to its organization and method of operation,together with further objects and advantages, will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, nature, and advantages of the present disclosure willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout.

FIG. 1 is a block diagram conceptually illustrating an example of atelecommunications system.

FIG. 2 is a diagram conceptually illustrating an example of a downlinkframe structure in a telecommunications system.

FIG. 3 is a block diagram conceptually illustrating an example framestructure in uplink communications.

FIG. 4 is a block diagram conceptually illustrating a design of a basestation/eNodeB and a UE configured according to an aspect of the presentdisclosure.

FIG. 5 is a block diagram conceptually illustrating adaptive resourcepartitioning in a heterogeneous network according to one aspect of thedisclosure.

FIGS. 6A-6C are block diagrams illustrating methods for configuringremote radio heads (RRHs) to determine positioning locations.

FIG. 7-9 are diagrams illustrating examples of a hardware implementationfor an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

The techniques described herein may be used for various wirelesscommunication networks such as Code Division Multiple Access (CDMA),Time Division Multiple Access (TDMA), Frequency Division Multiple Access(FDMA), Orthogonal Frequency Division Multiple Access (OFDMA),Single-Carrier Frequency Division Multiple Access (SC-FDMA) and othernetworks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology, suchas Universal Terrestrial Radio Access (UTRA), TelecommunicationsIndustry Association's (TIA's) CDMA2000®, and the like. The UTRAtechnology includes Wideband CDMA (WCDMA) and other variants of CDMA.The CDMA2000® technology includes the IS-2000, IS-95 and IS-856standards from the Electronics Industry Alliance (EIA) and TIA. A TDMAnetwork may implement a radio technology, such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology, such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, andthe like. The UTRA and E-UTRA technologies are part of Universal MobileTelecommunication System (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A) are newer releases of the UMTS that use E-UTRA.UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents froman organization called the “3rd Generation Partnership Project” (3GPP).CDMA2000® and UMB are described in documents from an organization calledthe “3rd Generation Partnership Project 2” (3GPP2). The techniquesdescribed herein may be used for the wireless networks and radio accesstechnologies mentioned above, as well as other wireless networks andradio access technologies. For clarity, certain aspects of thetechniques are described below for LTE or LTE-A (together referred to inthe alternative as “LTE/-A”) and use such LTE/-A terminology in much ofthe description below.

FIG. 1 shows a wireless communication network 100, which may be an LTE-Anetwork, with configurable remote radio heads. The wireless network 100includes a number of evolved node Bs (eNodeBs) 110 and other networkentities. An eNodeB may be a station that communicates with the UEs andmay also be referred to as a base station, a node B, an access point,and the like. Each eNodeB 110 may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to thisparticular geographic coverage area of an eNodeB and/or an eNodeBsubsystem serving the coverage area, depending on the context in whichthe term is used.

An eNodeB may provide communication coverage for a macro cell, a picocell, a femto cell, and/or other types of cell. A macro cell generallycovers a relatively large geographic area (e.g., several kilometers inradius) and may allow unrestricted access by UEs with servicesubscriptions with the network provider. A pico cell would generallycover a relatively smaller geographic area and may allow unrestrictedaccess by UEs with service subscriptions with the network provider. Afemto cell would also generally cover a relatively small geographic area(e.g., a home) and, in addition to unrestricted access, may also providerestricted access by UEs having an association with the femto cell(e.g., UEs in a closed subscriber group (CSG), UEs for users in thehome, and the like). An eNodeB for a macro cell may be referred to as amacro eNodeB. An eNodeB for a pico cell may be referred to as a picoeNodeB. And, an eNodeB for a femto cell may be referred to as a femtoeNodeB or a home eNodeB. In the example shown in FIG. 1, the eNodeBs 110a, 110 b and 110 c are macro eNodeBs for the macro cells 102 a, 102 band 102 c, respectively. The eNodeB 110 x is a pico eNodeB for a picocell 102 x. And, the eNodeBs 110 y and 110 z are femto eNodeBs for thefemto cells 102 y and 102 z, respectively. An eNodeB may support one ormultiple (e.g., two, three, four, and the like) cells.

The wireless network 100 may also include relay stations. A relaystation is a station that receives a transmission of data and/or otherinformation from an upstream station (e.g., an eNodeB, UE, etc.) andsends a transmission of the data and/or other information to adownstream station (e.g., a UE or an eNodeB). A relay station may alsobe a UE that relays transmissions for other UEs. In the example shown inFIG. 1, a relay station 110 r may communicate with the eNodeB 110 a anda UE 120 r in order to facilitate communication between the eNodeB 110 aand the UE 120 r. A relay station may also be referred to as a relayeNodeB, a relay, etc.

The wireless network 100 may be a heterogeneous network that includeseNodeBs of different types, e.g., macro eNodeBs, pico eNodeBs, femtoeNodeBs, relays, etc. These different types of eNodeBs may havedifferent transmit power levels, different coverage areas, and differentimpact on interference in the wireless network 100. For example, macroeNodeBs may have a high transmit power level (e.g., 20 Watts) whereaspico eNodeBs, femto eNodeBs and relays may have a lower transmit powerlevel (e.g., 1 Watt).

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the eNodeBs may have similar frametiming, and transmissions from different eNodeBs may be approximatelyaligned in time. For asynchronous operation, the eNodeBs may havedifferent frame timing, and transmissions from different eNodeBs may notbe aligned in time. The techniques described herein may be used foreither synchronous or asynchronous operations.

In one aspect, the wireless network 100 may support Frequency DivisionDuplex (FDD) or Time Division Duplex (TDD) modes of operation. Thetechniques described herein may be used for FDD or TDD mode ofoperation.

A network controller 130 may couple to a set of eNodeBs 110 and providecoordination and control for these eNodeBs 110. The network controller130 may communicate with the eNodeBs 110 via a backhaul. The eNodeBs 110may also communicate with one another, e.g., directly or indirectly viaa wireless backhaul or a wireline backhaul.

The UEs 120 (e.g., UE 120 x, UE 120 y, etc.) are dispersed throughoutthe wireless network 100, and each UE may be stationary or mobile. A UEmay also be referred to as a terminal, a user terminal, a mobilestation, a subscriber unit, a station, or the like. A UE may be acellular phone (e.g., a smart phone), a personal digital assistant(PDA), a wireless modem, a wireless communication device, a handhelddevice, a laptop computer, a cordless phone, a wireless local loop (WLL)station, a tablet, a netbook, a smart book, or the like. A UE may beable to communicate with macro eNodeBs, pico eNodeBs, femto eNodeBs,relays, and the like. In FIG. 1, a solid line with double arrowsindicates desired transmissions between a UE and a serving eNodeB, whichis an eNodeB designated to serve the UE on the downlink and/or uplink. Adashed line with double arrows indicates interfering transmissionsbetween a UE and an eNodeB.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on thedownlink and single-carrier frequency division multiplexing (SC-FDM) onthe uplink. OFDM and SC-FDM partition the system bandwidth into multiple(K) orthogonal subcarriers, which are also commonly referred to astones, bins, or the like. Each subcarrier may be modulated with data. Ingeneral, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. The spacing between adjacentsubcarriers may be fixed, and the total number of subcarriers (K) may bedependent on the system bandwidth. For example, the spacing of thesubcarriers may be 15 kHz and the minimum resource allocation (called a‘resource block’) may be 12 subcarriers (or 180 kHz). Consequently, thenominal FFT size may be equal to 128, 256, 512, 1024 or 2048 for acorresponding system bandwidth of 1.25, 2.5, 5, 10 or 20 megahertz(MHz), respectively. The system bandwidth may also be partitioned intosub-bands. For example, a sub-band may cover 1.08 MHz (i.e., 6 resourceblocks), and there may be 1, 2, 4, 8 or 16 sub-bands for a correspondingsystem bandwidth of 1.25, 2.5, 5, 10, 15 or 20 MHz, respectively.

FIG. 2 shows a downlink FDD frame structure used in LTE. Thetransmission timeline for the downlink may be partitioned into units ofradio frames. Each radio frame may have a predetermined duration (e.g.,10 milliseconds (ms)) and may be partitioned into 10 subframes withindices of 0 through 9. Each subframe may include two slots. Each radioframe may thus include 20 slots with indices of 0 through 19. Each slotmay include L symbol periods, e.g., 7 symbol periods for a normal cyclicprefix (as shown in FIG. 2) or 6 symbol periods for an extended cyclicprefix. The 2L symbol periods in each subframe may be assigned indicesof 0 through 2L−1. The available time frequency resources may bepartitioned into resource blocks. Each resource block may cover Nsubcarriers (e.g., 12 subcarriers) in one slot.

In LTE, an eNodeB may send a primary synchronization signal (PSC or PSS)and a secondary synchronization signal (SSC or SSS) for each cell in theeNodeB. For FDD mode of operation, the primary and secondarysynchronization signals may be sent in symbol periods 6 and 5,respectively, in each of subframes 0 and 5 of each radio frame with thenormal cyclic prefix, as shown in FIG. 2. The synchronization signalsmay be used by UEs for cell detection and acquisition. For FDD mode ofoperation, the eNodeB may send a Physical Broadcast Channel (PBCH) insymbol periods 0 to 3 in slot 1 of subframe 0. The PBCH may carrycertain system information.

The eNodeB may send a Physical Control Format Indicator Channel (PCFICH)in the first symbol period of each subframe, as seen in FIG. 2. ThePCFICH may convey the number of symbol periods (M) used for controlchannels, where M may be equal to 1, 2 or 3 and may change from subframeto subframe. M may also be equal to 4 for a small system bandwidth,e.g., with less than 10 resource blocks. In the example shown in FIG. 2,M=3. The eNodeB may send a Physical HARQ Indicator Channel (PHICH) and aPhysical Downlink Control Channel (PDCCH) in the first M symbol periodsof each subframe. The PDCCH and PHICH are also included in the firstthree symbol periods in the example shown in FIG. 2. The PHICH may carryinformation to support hybrid automatic repeat request (HARQ). The PDCCHmay carry information on uplink and downlink resource allocation for UEsand power control information for uplink channels. The eNodeB may send aPhysical Downlink Shared Channel (PDSCH) in the remaining symbol periodsof each subframe. The PDSCH may carry data for UEs scheduled for datatransmission on the downlink.

The eNodeB may send the PSC, SSC and PBCH in the center 1.08 MHz of thesystem bandwidth used by the eNodeB. The eNodeB may send the PCFICH andPHICH across the entire system bandwidth in each symbol period in whichthese channels are sent. The eNodeB may send the PDCCH to groups of UEsin certain portions of the system bandwidth. The eNodeB may send thePDSCH to groups of UEs in specific portions of the system bandwidth. TheeNodeB may send the PSC, SSC, PBCH, PCFICH and PHICH in a broadcastmanner to all UEs, may send the PDCCH in a unicast manner to specificUEs, and may also send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period.Each resource element may cover one subcarrier in one symbol period andmay be used to send one modulation symbol, which may be a real orcomplex value. For symbols that are used for control channels, theresource elements not used for a reference signal in each symbol periodmay be arranged into resource element groups (REGs). Each REG mayinclude four resource elements in one symbol period. The PCFICH mayoccupy four REGs, which may be spaced approximately equally acrossfrequency, in symbol period 0. The PHICH may occupy three REGs, whichmay be spread across frequency, in one or more configurable symbolperiods. For example, the three REGs for the PHICH may all belong insymbol period 0 or may be spread in symbol periods 0, 1 and 2. The PDCCHmay occupy 9, 18, 36 or 72 REGs, which may be selected from theavailable REGs, in the first M symbol periods. Only certain combinationsof REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. TheUE may search different combinations of REGs for the PDCCH. The numberof combinations to search is typically less than the number of allowedcombinations for all UEs in the PDCCH. An eNodeB may send the PDCCH tothe UE in any of the combinations that the UE will search.

A UE may be within the coverage of multiple eNodeBs. One of theseeNodeBs may be selected to serve the UE. The serving eNodeB may beselected based on various criteria such as received power, path loss,signal-to-noise ratio (SNR), etc.

FIG. 3 is a block diagram conceptually illustrating an exemplary FDD andTDD (non-special subframe only) subframe structure in uplink long termevolution (LTE) communications. The available resource blocks (RBs) forthe uplink may be partitioned into a data section and a control section.The control section may be formed at the two edges of the systembandwidth and may have a configurable size. The resource blocks in thecontrol section may be assigned to UEs for transmission of controlinformation. The data section may include all resource blocks notincluded in the control section. The design in FIG. 3 results in thedata section including contiguous subcarriers, which may allow a singleUE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned resource blocks in the control section to transmitcontrol information to an eNodeB. The UE may also be assigned resourceblocks in the data section to transmit data to the eNode B. The UE maytransmit control information in a Physical Uplink Control Channel(PUCCH) on the assigned resource blocks in the control section. The UEmay transmit only data or both data and control information in aPhysical Uplink Shared Channel (PUSCH) on the assigned resource blocksin the data section. An uplink transmission may span both slots of asubframe and may hop across frequency as shown in FIG. 3. According toone aspect, in relaxed single carrier operation, parallel channels maybe transmitted on the UL resources. For example, a control and a datachannel, parallel control channels, and parallel data channels may betransmitted by a UE.

The PSC (primary synchronization carrier), SSC (secondarysynchronization carrier), CRS (common reference signal), PBCH, PUCCH,PUSCH, and other such signals and channels used in LTE/-A are describedin 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation,” which is publiclyavailable.

FIG. 4 shows a block diagram of a design of a base station/eNodeB 110and a UE 120, which may be one of the base stations/eNodeBs and one ofthe UEs in FIG. 1. For example, the base station 110 may be the macroeNodeB 110 c in FIG. 1, and the UE 120 may be the UE 120 y. The basestation 110 may also be a base station of some other type, such as aremote radio head (RRH), pico eNodeB 110 x or femto eNodeB 110 y. Thebase station 110 may be equipped with antennas 434 a through 434 t, andthe UE 120 may be equipped with antennas 452 a through 452 r.

At the base station 110, a transmit processor 420 may receive data froma data source 412 and control information from a controller/processor440. The control information may be for the PBCH, PCFICH, PHICH, PDCCH,etc. The data may be for the PDSCH, etc. The processor 420 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The processor 420 mayalso generate reference symbols, e.g., for the PSS, SSS, andcell-specific reference signal. A transmit (TX) multiple-inputmultiple-output (MIMO) processor 430 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, and/or thereference symbols, if applicable, and may provide output symbol streamsto the modulators (MODs) 432 a through 432 t. Each modulator 432 mayprocess a respective output symbol stream (e.g., for OFDM, etc.) toobtain an output sample stream. Each modulator 432 may further process(e.g., convert to analog, amplify, filter, and upconvert) the outputsample stream to obtain a downlink signal. Downlink signals frommodulators 432 a through 432 t may be transmitted via the antennas 434 athrough 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) 454 a through 454 r, respectively. Eachdemodulator 454 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 454 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 456 may obtainreceived symbols from all the demodulators 454 a through 454 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 458 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 120 to a data sink 460, and provide decoded control informationto a controller/processor 480.

On the uplink, at the UE 120, a transmit processor 464 may receive andprocess data (e.g., for the PUSCH) from a data source 462 and controlinformation (e.g., for the PUCCH) from the controller/processor 480. Theprocessor 464 may also generate reference symbols for a referencesignal. The symbols from the transmit processor 464 may be precoded by aTX MIMO processor 466 if applicable, further processed by the modulators454 a through 454 r (e.g., for SC-FDM, etc.), and transmitted to thebase station 110. At the base station 110, the uplink signals from theUE 120 may be received by the antennas 434, processed by thedemodulators 432, detected by a MIMO detector 436 if applicable, andfurther processed by a receive processor 438 to obtain decoded data andcontrol information sent by the UE 120. The processor 438 may providethe decoded data to a data sink 439 and the decoded control informationto the controller/processor 440. The base station 110 can send messagesto other base stations, for example, over an X2 interface 441.

The controllers/processors 440 and 480 may direct the operation at thebase station 110 and the UE 120, respectively. The processor 440/480and/or other processors and modules at the base station 110/UE 120 mayperform or direct the execution of the functional blocks illustrated inmethod flow chart FIGS. 6A and 6B, and/or other processes for thetechniques described herein. The memories 442 and 482 may store data andprogram codes for the base station 110 and the UE 120, respectively. Ascheduler 444 may schedule UEs for data transmission on the downlinkand/or uplink.

Heterogeneous Network

Wireless networks may have eNodeBs of different power classes. Forexample, three power classes may be defined, in decreasing power class,as macro eNodeBs, pico eNodeBs, and femto eNodeBs. Networks featuringsuch different power class eNodeBs may be referred to as heterogeneousnetworks. When macro eNodeBs, pico eNodeBs, and femto eNodeBs are in aco-channel deployment, the power spectral density (PSD) of the macroeNodeB (aggressor eNodeB) may be larger than the PSD of the pico eNodeBand the femto eNodeB (victim eNodeBs) creating large amounts ofinterference with the pico eNodeB and the femto eNodeB. Protectedsubframes may be used to reduce or minimize interference with the picoeNodeBs and femto eNodeBs. That is, a protected subframe may bescheduled for the victim eNodeB to correspond with a prohibited subframeon the aggressor eNodeB.

Referring back to FIG. 1, the heterogeneous wireless network 100 usesthe diverse set of eNodeBs 110 (i.e., macro eNodeBs, pico eNodeBs, femtoeNodeBs, and relays) to improve the spectral efficiency of the systemper unit area. The macro eNodeBs 110 a-c are usually carefully plannedand placed by the provider of the wireless network 100. The macroeNodeBs 110 a-c generally transmit at high power levels (e.g., 5 W-40W). The pico eNodeB 110 x and the relay 110 r, which generally transmitat substantially lower power levels (e.g., 100 mW-2 W), may be deployedin a relatively unplanned manner to eliminate coverage holes in thecoverage area provided by the macro eNodeBs 110 a-c and improve capacityin the hot spots. The femto eNodeBs 110 y-z, which are typicallydeployed independently from the wireless network 100 may, nonetheless,be incorporated into the coverage area of the wireless network 100either as a potential access point to the wireless network 100, ifauthorized by their administrator(s), or at least as an active and awareeNodeB that may communicate with the other eNodeBs 110 of the wirelessnetwork 100 to perform resource coordination and coordination ofinterference management. The femto eNodeBs 110 y-z typically alsotransmit at substantially lower power levels (e.g., 100 mW-2 W) than themacro eNodeBs 110 a-c.

In operation of a heterogeneous network, such as the wireless network100, each UE is usually served by the eNodeB 110 with the better signalquality, while the unwanted signals received from the other eNodeBs 110are treated as interference. While such operational principals can leadto significantly sub-optimal performance, gains in network performanceare realized in the wireless network 100 by using intelligent resourcecoordination among the eNodeBs 110, better server selection strategies,and more advanced techniques for efficient interference management.

A pico eNodeB, such as the pico eNodeB 110 x, is characterized by asubstantially lower transmit power when compared with a macro eNodeB,such as the macro eNodeBs 110 a-c. A pico eNodeB will also usually beplaced around a network, such as the wireless network 100, in an ad hocmanner. Because of this unplanned deployment, wireless networks withpico eNodeB placements, such as the wireless network 100, can beexpected to have large areas with low signal to interference conditions,which can make for a more challenging RF environment for control channeltransmissions to UEs on the edge of a coverage area or cell (a“cell-edge” UE). Moreover, the potentially large disparity (e.g.,approximately 20 dB) between the transmit power levels of the macroeNodeBs 110 a-c and the pico eNodeB 110 x implies that, in a mixeddeployment, the downlink coverage area of the pico eNodeB 110 x will bemuch smaller than that of the macro eNodeBs 110 a-c.

In the uplink case, however, the signal strength of the uplink signal isgoverned by the UE, and, thus, will be similar when received by any typeof the eNodeBs 110. With the uplink coverage areas for the eNodeBs 110being roughly the same or similar, uplink handoff boundaries will bedetermined based on channel gains. This can lead to a mismatch betweendownlink handover boundaries and uplink handover boundaries. Withoutadditional network accommodations, the mismatch would make the serverselection or the association of UE to eNodeB more difficult in thewireless network 100 than in a macro eNodeB-only homogeneous network,where the downlink and uplink handover boundaries are more closelymatched.

Range Extension

If server selection is based predominantly on downlink received signalstrength, as provided in the LTE Release 8 standard, the usefulness ofmixed eNodeB deployment of heterogeneous networks, such as the wirelessnetwork 100, will be greatly diminished. This is because the largercoverage area of the higher powered macro eNodeBs, such as the macroeNodeBs 110 a-c, limits the benefits of splitting the cell coverage withthe pico eNodeBs, such as the pico eNodeB 110 x, because, the higherdownlink received signal strength of the macro eNodeBs 110 a-c willattract all of the available UEs, while the pico eNodeB 110 x may not beserving any UE because of its much weaker downlink transmission power.Moreover, the macro eNodeBs 110 a-c will likely not have sufficientresources to efficiently serve those UEs. Therefore, the wirelessnetwork 100 will attempt to actively balance the load between the macroeNodeBs 110 a-c and the pico eNodeB 110 x by expanding the coverage areaof the pico eNodeB 110 x. This concept is referred to as rangeextension.

The wireless network 100 achieves this range extension by changing themanner in which server selection is determined. Instead of basing serverselection on downlink received signal strength, selection is based moreon the quality of the downlink signal. In one such quality-baseddetermination, server selection may be based on determining the eNodeBthat offers the minimum path loss to the UE. Additionally, the wirelessnetwork 100 provides a fixed partitioning of resources equally betweenthe macro eNodeBs 110 a-c and the pico eNodeB 110 x. However, even withthis active balancing of load, downlink interference from the macroeNodeBs 110 a-c should be mitigated for the UEs served by the picoeNodeBs, such as the pico eNodeB 110 x. This can be accomplished byvarious methods, including interference cancellation at the UE, resourcecoordination among the eNodeBs 110, or the like.

In a heterogeneous network with range extension, such as the wirelessnetwork 100, in order for UEs to obtain service from the lower-poweredeNodeBs, such as the pico eNodeB 110 x, in the presence of the strongerdownlink signals transmitted from the higher-powered eNodeBs, such asthe macro eNodeBs 110 a-c, the pico eNodeB 110 x engages in controlchannel and data channel interference coordination with the dominantinterfering ones of the macro eNodeBs 110 a-c. Many different techniquesfor interference coordination may be employed to manage interference.For example, inter-cell interference coordination (ICIC) may be used toreduce interference from cells in co-channel deployment. One ICICmechanism is adaptive resource partitioning. Adaptive resourcepartitioning assigns subframes to certain eNodeBs. In subframes assignedto a first eNodeB, neighbor eNodeBs do not transmit. Thus, interferenceexperienced by a UE served by the first eNodeB is reduced. Subframeassignment may be performed on both the uplink and downlink channels.

Adaptive Resource Partitioning

For example, subframes may be allocated between three classes ofsubframes: protected subframes (U subframes), prohibited subframes (Nsubframes), and common subframes (C subframes). Protected subframes areassigned to a first eNodeB for use exclusively by the first eNodeB.Protected subframes may also be referred to as “clean” subframes basedon the lack of interference from neighboring eNodeBs. Prohibitedsubframes are subframes assigned to a neighbor eNodeB, and the firsteNodeB is prohibited from transmitting data during the prohibitedsubframes. For example, a prohibited subframe of the first eNodeB maycorrespond to a protected subframe of a second interfering eNodeB. Thus,the first eNodeB is the only eNodeB transmitting data during the firsteNodeB's protected subframe. Common subframes may be used for datatransmission by multiple eNodeBs. Common subframes may also be referredto as “unclean” subframes because of the possibility of interferencefrom other eNodeBs.

At least one protected subframe is statically assigned per period. Insome cases only one protected subframe is statically assigned. Forexample, if a period is 8 milliseconds, one protected subframe may bestatically assigned to an eNodeB during every 8 milliseconds. Othersubframes may be dynamically allocated.

Adaptive resource partitioning information (ARPI) allows thenon-statically assigned subframes to be dynamically allocated. Any ofprotected, prohibited, or common subframes may be dynamically allocated(AU, AN, AC subframes, respectively). The dynamic assignments may changequickly, such as, for example, every one hundred milliseconds or less.

FIG. 5 is a block diagram illustrating TDM partitioning in aheterogeneous network according to one aspect of the disclosure. A firstrow of blocks illustrate sub frame assignments for a femto eNodeB, and asecond row of blocks illustrate sub frame assignments for a macroeNodeB. Each of the eNodeBs has a static protected sub frame duringwhich the other eNodeB has a static prohibited sub frame. For example,the femto eNodeB has a protected sub frame (U sub frame) in sub frame 0corresponding to a prohibited sub frame (N sub frame) in sub frame 0.Likewise, the macro eNodeB has a protected sub frame (U sub frame) insub frame 7 corresponding to a prohibited sub frame (N sub frame) in subframe 7. Sub frames 1-6 are dynamically assigned as either protected subframes (AU), prohibited sub frames (AN), and common sub frames (AC). Thedynamically assigned subframes (AU/AN/AC) are referred to hereincollectively as “X” subframes. During the dynamically assigned commonsub frames (AC) in sub frames 5 and 6, both the femto eNodeB and themacro eNodeB may transmit data.

Protected sub frames (such as U/AU sub frames) have reduced interferenceand a high channel quality because aggressor eNodeBs are prohibited fromtransmitting. Prohibited sub frames (such as N/AN sub frames) have nodata transmission to allow victim eNodeBs to transmit data with lowinterference levels. Common sub frames (such as C/AC sub frames) have achannel quality dependent on the number of neighbor eNodeBs transmittingdata. For example, if neighbor eNodeBs are transmitting data on thecommon sub frames, the channel quality of the common sub frames may belower than the protected sub frames. Channel quality on common subframes may also be lower for extended boundary area (EBA) UEs stronglyaffected by aggressor eNodeBs. An EBA UE may belong to a first eNodeBbut also be located in the coverage area of a second eNodeB. Forexample, a UE communicating with a macro eNodeB that is near the rangelimit of a femto eNodeB coverage is an EBA UE.

Another example interference management scheme that may be employed inLTE/-A is the slowly-adaptive interference management. Using thisapproach to interference management, resources are negotiated andallocated over time scales that are much larger than the schedulingintervals. The goal of the scheme is to find a combination of transmitpowers for all of the transmitting eNodeBs and UEs over all of the timeor frequency resources that maximizes the total utility of the network.“Utility” may be defined as a function of user data rates, delays ofquality of service (QoS) flows, and fairness metrics. Such an algorithmcan be computed by a central entity that has access to all of theinformation used for solving the optimization and has control over allof the transmitting entities, such as, for example, the networkcontroller 130 (FIG. 1). This central entity may not always be practicalor even desirable. Therefore, in alternative aspects a distributedalgorithm may be used that makes resource usage decisions based on thechannel information from a certain set of nodes. Thus, theslowly-adaptive interference algorithm may be deployed either using acentral entity or by distributing the algorithm over various sets ofnodes/entities in the network.

In deployments of heterogeneous networks, such as the wireless network100, a UE may operate in a dominant interference scenario in which theUE may observe high interference from one or more interfering eNodeBs. Adominant interference scenario may occur due to restricted association.For example, in FIG. 1, the UE 120 y may be close to the femto eNodeB110 y and may have high received power for the eNodeB 110 y. However,the UE 120 y may not be able to access the femto eNodeB 110 y due torestricted association and may then connect to the macro eNodeB 110 c(as shown in FIG. 1) or to the femto eNodeB 110 z also with lowerreceived power (not shown in FIG. 1). The UE 120 y may then observe highinterference from the femto eNodeB 110 y on the downlink and may alsocause high interference to the eNodeB 110 y on the uplink. Usingcoordinated interference management, the eNodeB 110 c and the femtoeNodeB 110 y may communicate over the backhaul to negotiate resources.In the negotiation, the femto eNodeB 110 y agrees to cease transmissionon one of its channel resources, such that the UE 120 y will notexperience as much interference from the femto eNodeB 110 y as itcommunicates with the eNodeB 110 c over that same channel.

In addition to the discrepancies in signal power observed at the UEs insuch a dominant interference scenario, timing delays of downlink signalsmay also be observed by the UEs, even in synchronous systems, because ofthe differing distances between the UEs and the multiple eNodeBs. TheeNodeBs in a synchronous system are presumptively synchronized acrossthe system. However, for example, considering a UE that is a distance of5 km from the macro eNodeB, the propagation delay of any downlinksignals received from that macro eNodeB would be delayed approximately16.67 μs (5 km÷3×108, i.e., the speed of light, ‘c’). Comparing thatdownlink signal from the macro eNodeB to the downlink signal from a muchcloser femto eNodeB, the timing difference could approach the level of atime tracking loop (TTL) error.

Additionally, such timing difference may impact the interferencecancellation at the UE. Interference cancellation often uses crosscorrelation properties between a combination of multiple versions of thesame signal. By combining multiple copies of the same signal,interference may be more easily identified because, while there willlikely be interference on each copy of the signal, it will likely not bein the same location. Using the cross correlation of the combinedsignals, the actual signal portion may be determined and distinguishedfrom the interference, thus, allowing the interference to be canceled.

Positioning Location for Remote Radio Heads (RRH) with Same PhysicalCell Identity (PCI)

Currently, a UE's location is determined by the network. A positionlocation server may rely on a UE to detect a time difference betweensignals received from various macro base stations. The UE reports thedetected time difference back to the position location server. Thelocation server then compiles the received data and throughtriangulation determines the location of the UE. One example systemincludes one or more remote radio head (RRH), which is similar to a basestation of a pico cell, and one or more macro eNodeB (eNodeB), which isa base station of a macro cell. In some configurations, such as CoMP(coordinated multi point) configurations, the remote radio heads andmacro eNodeB have the same physical cell ID (PCI). A position referencesignal (PRS) is generated based on or derived from the physical cell IDof the transmitting node (e.g. RRH, pico cell, or macro eNodeB). Whenthe resulting position reference signals (PRSs) transmitted from theremote radio heads and macro cells is the same, then determining theposition location of the UE may be affected. For example, if the UE isfar from the eNodeB, but close to the remote radio head, the UE reportsback the position reference signal from the eNodeB, which is the same asthe position reference signal from the remote radio head. Consequently,the location server will interpret the information incorrectly, asthough the UE is near the eNodeB. The present disclosure helps preventdifferent nodes from transmitting the same position reference signal(PRS).

In one aspect of the present disclosure, the position location referencesignal (PRS) transmissions from the remote radio head are silenced. Inother words, the remote radio head does not transmit the positionreference signal. This allows the macro eNodeB to transmit the positionreference signal and the UE to respond accurately. Silencing theposition reference signal transmission does not involve any input fromthe network side. Advantages of this solution include easy scaling atthe location server and not having to re-plan position reference signalre-use. In another aspect, all nodes with the same position referencesignal, except the highest power node, may be silenced. For example, inaspects where the eNodeB has the highest power, the lower powered remoteradio heads are silenced. In some aspects, only nodes considered lowpower nodes (e.g., RRHs, pico cells and femto cells), with the sameposition reference signal are silenced.

In another aspect, a new identification is assigned to each remote radiohead. In particular, in one configuration, a new virtual identification(ID) is assigned to each remote radio head and eNodeB. The virtual ID,not the PCI (physical cell ID), is then used to generate the positionreference signal, resulting in different position reference signals forthe remote radio heads and eNodeB. This provides a known location forthe remote radio head, which may increase accuracy for determiningposition location.

In another aspect, an identifier such as the cell global identification(CGI) of each remote radio head and eNodeB may be used to generate theposition reference signal. The cell global identification (CGI) may alsobe referred to as a global cell identification (GCI). Using the cellglobal identification (CGI) to generate the position reference signalprovides a known location for the remote radio head, which again mayincrease accuracy for determining position location. Additionally reuseis coordinated and CGIs are provided that do not collide with existingIDs. The location server may configure the remote radio heads indifferent macro cells to avoid CGI collision. The UE may be informed ofthe position reference signal configuration of at least one macro celland one or more remote radio heads. Thus, the UEs are aware of whichcells to measure. The UEs that are close to a neighboring macro cell mayalso be informed of the position reference signal configurations ofneighboring macros cells.

In yet another aspect, a schedule or pattern is mapped that illustrateswhen each of the nodes is broadcasting a position reference signal. TheUE is informed of this mapping function and the position of the UE canthen be calculated because the UE knows from which node the positionreference signal was transmitted, even though the position referencesignal itself may not identify (or explicitly reveal) which nodetransmitted the signal. In this configuration, the UE location can bedetermined even if the nodes are transmitting the same positionreference signal, because not all the nodes are transmitting theposition reference signals at the same time.

In another example, uplink transmissions are used for locationdeterminations. For example, the reference time signal difference (RSTD)may be measured at each node for triangulation based on soundingreference signals (SRSs), physical uplink control channel (PUCCH)transmissions or physical uplink shared channel (PUSCH) transmissions.In one example, the macro cell and associated remote radio head locationis known by the location server. Additionally, in another example, theposition location based on uplink data may be merged with downlinkmeasurements when the remote radio head position reference signaltransmissions are silenced or when the position reference signal isderived from a unique virtual ID or the assigned cell globalidentification (CGI).

FIGS. 6A-6C are block diagrams illustrating methods for configuringremote radio heads. FIG. 6A provides a method 601 where multiple remoteradio heads (RRHs) are configured. At block, 610 the RRHs are configuredto prevent position reference signal (PRS) transmissions on the samesubframes where a macro eNodeB transmits PRS. The RRHs having the samephysical cell ID (PCI) as a macro eNodeB, and a lower power than themacro eNodeB, are configured. Transmissions may be prevented bysilencing the PRS transmissions or by configuring the RRHs not totransmit PRS. At block 612, the remote radio heads communicate inaccordance with the configuration.

In FIG. 6B, a method 602 is illustrated. At block 620, the remote radioheads (RRHs) are configured. At block 622, the RRHs receive uplinktransmissions from a UE (user equipment). At block 624, the positionlocation of a UE is determined based on received signal time difference(RSTD) measurements of the uplink transmissions at the RRHs and macroeNodeB.

In FIG. 6C, a method 603 is provided. At block 620, a unique positionlocation reference signal (PRS) is generated for each remote radio head(RRH) based on a virtual cell ID or unique cell global identifications(CGIs) of each of the remote radio heads. At block 622, the remote radioheads transmit the unique position location reference signals.

FIGS. 7-9 are diagrams illustrating an example of a hardwareimplementation for an apparatus 700, 800, 900 employing a processingsystem 714, 814, 914. The processing system 714, 814, 914 may beimplemented with a bus architecture, represented generally by the bus724, 824, 924. The bus 724, 824, 924 may include any number ofinterconnecting buses and bridges depending on the specific applicationof the processing system 714, 814, 914 and the overall designconstraints. The bus 724, 824, 924 links together various circuitsincluding one or more processors and/or hardware modules, represented bythe processor 708, 808, 908, the modules 702, 704, 802, 804, 902, 904and the computer-readable medium 706, 806, 906. The bus 724, 824, 924may also link various other circuits such as timing sources,peripherals, voltage regulators, and power management circuits, whichare well known in the art, and therefore, will not be described anyfurther.

The apparatus includes a processing system 714, 814, 914 coupled to atransceiver 710, 810, 910. The transceiver 710, 810, 910 is coupled toone or more antennas 720, 820, 920. The transceiver 710, 810, 910enables communicating with various other apparatus over a transmissionmedium. The processing system 714, 814, 914 includes a processor 708,808, 908 coupled to a computer-readable medium 706, 806, 906. Theprocessor 708, 808, 908 is responsible for general processing, includingthe execution of software stored on the computer-readable medium 706,806, 906. The software, when executed by the processor 708, 808, 908causes the processing system 714, 814, 914 to perform the variousfunctions described for any particular apparatus. The computer-readablemedium 706, 806, 906 may also be used for storing data that ismanipulated by the processor 708, 808, 908 when executing software.

The processing system of FIG. 7 includes a configuring module 702 and acommunicating module 704. The configuring module can configure remoteradio heads (RRHs), each having the same physical cell ID as a macroeNodeB, to prevent position location reference signal (PRS)transmissions on the subframes where a macro eNodeB is transmitting PRS.The communicating module can cause the remote radio heads to communicatein accordance with the configuration. The modules may be softwaremodules running in the processor 708, resident/stored in thecomputer-readable medium 706, one or more hardware modules coupled tothe processor 708, or some combination thereof. The processing system714 may be a component of the eNodeB 110, 110 x, 110 y, and may includethe memory 442, the transmit processor 420, the receive processor 438,the modulators/demodulators 432 a-t, the antenna 434 a-t, and/or thecontroller/processor 440.

The processing system of FIG. 8 includes a configuring module 802, areceiving module 804 and a determining module 805. The configuringmodule can configure a plurality of remote radio heads (RRHs). Thereceiving module can receive uplink transmissions from a user equipment.The determining module can determine a position location of the UE. Themodules may be software modules running in the processor 808,resident/stored in the computer-readable medium 806, one or morehardware modules coupled to the processor 808, or some combinationthereof. The processing system 814 may be a component of the eNodeB 110,110 x, 110 y, and may include the memory 442, the transmit processor420, the receive processor 438, the modulators/demodulators 432 a-t, theantenna 434 a-t, and/or the controller/processor 440.

The processing system of FIG. 9 includes a generating module 902 and atransmitting module 904. The generating module can generate a uniqueposition location reference signal (PRS) for a remote radio head (RRH)based on a virtual cell ID or unique cell global identifications (CGIs)of the remote radio head. The transmitting module can cause the remoteradio head to transmit the unique position location signal. The modulesmay be software modules running in the processor 908, resident/stored inthe computer-readable medium 906, one or more hardware modules coupledto the processor 908, or some combination thereof. The processing system914 may be a component of the eNodeB 110, 110 x, 110 y, and may includethe memory 442, the transmit processor 420, the receive processor 438,the modulators/demodulators 432 a-t, the antenna 434 a-t, and/or thecontroller/processor 440.

In one configuration, an eNodeB 110 configures a remote radio head forwireless communication and includes a means for configuring. In oneaspect, the configuring means may be the transmit processor 420, themodulators 432 a-t, the antenna 434 a-t, the controller/processor 440,and/or the memory 442 configured to perform the functions recited by theconfiguring means. The eNodeB 110 is also configured to include a meansfor communicating. In one aspect, the communicating means may be thetransmit processor 420, the modulators 432 a-t, the antenna 434 a-t, thecontroller/processor 440, the memory 442 and/or the receive processor438 configured to perform the functions recited by the communicatingmeans. In another aspect, the aforementioned means may be any module orany apparatus configured to perform the functions recited by theaforementioned means.

In another configuration a base station 110 (e.g., a remote radio head)includes a means for configuring. In one aspect, the configuring meansmay be the transmit processor 420, the modulators 432 a-t, the antenna434 a-t, the controller/processor 440, and/or the memory 442 configuredto perform the functions recited by the configuring means. The eNodeB110 is also configured to include a means for receiving. In one aspect,the receiving means may be the antenna 434 a-t, the demodulators 432a-t, the MIMO detector 436, the receive processor 438, thecontroller/processor 440 and/or the memory 442 configured to perform thefunctions recited by the receiving means. In another aspect, theaforementioned means may be any module or any apparatus configured toperform the functions recited by the aforementioned means.

In another configuration, a base station 110 (e.g., a remote radio head)includes a means for generating. In one aspect, the generating means maybe the controller/processor 440, and/or the memory 442 configured toperform the functions recited by the configuring means. The base station110 is also configured to include a means for transmitting. In oneaspect, the transmitting means may be the transmit processor 420, themodulators 432 a-t, the antenna 434 a-t, the controller/processor 440,and/or the memory 442 configured to perform the functions recited by thecommunicating means. In another aspect, the aforementioned means may beany module or any apparatus configured to perform the functions recitedby the aforementioned means.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of wireless communication, comprising:generating a unique position reference signal (PRS) for a remote radiohead having a same physical cell identity (PCI) as a macro eNodeB, theunique PRS being based on at least one of a virtual cell ID or uniquecell global identification (CGI) of the remote radio head such that theunique PRS is different from a PRS of the macro eNodeB, the PRS of themacro eNodeB being based on the PCI; and transmitting the unique PRS. 2.The method of claim 1, further comprising signaling to a user equipment(UE) that the PRS is based on at least one of the cell globalidentification or the virtual cell ID.
 3. The method of claim 1, furthercomprising signaling to a user equipment (UE), a position referencesignal configuration of a plurality of remote radio heads in neighboringcells when the UE is near a serving cell boundary.
 4. The method ofclaim 1, further comprising receiving uplink transmissions from a userequipment (UE); and determining a position location of the UE based onthe received uplink transmissions.
 5. An apparatus for wirelesscommunication, comprising: a memory; and at least one processor coupledto the memory, the at least one processor being configured: to generatea unique position reference signal (PRS) for a remote radio head (RRH)having a same physical cell identity (PCI) as a macro eNodeB, the uniquePRS being based on at least one of a virtual cell ID or unique cellglobal identification (CGI) of the remote radio head such that theunique PRS is different from a PRS of the macro eNodeB, the PRS of themacro eNodeB being based on the PCI; and to transmit the unique PRS. 6.The apparatus of claim 5, in which the processor is further configuredto signal to a user equipment (UE) that the PRS is based on at least oneof the cell global identification or the virtual cell ID.
 7. Theapparatus of claim 5, in which the processor is further configured tosignal to a user equipment (UE), a position reference signalconfiguration of a plurality of remote radio heads in neighboring cellswhen the UE is near a serving cell boundary.
 8. The apparatus of claim5, in which the processor is further configured: to receive uplinktransmissions from a user equipment (UE); and to determine a positionlocation of the UE based on the received uplink transmissions.
 9. Acomputer program product for wireless communication in a wirelessnetwork, comprising: a non-transitory computer-readable medium havingnon-transitory program code recorded thereon, the program codecomprising: program code to generate a unique position reference signal(PRS) for a remote radio head (RRH) having a same physical cell identity(PCI) as a macro eNodeB, the unique PRS being based on at least one of avirtual cell ID or unique cell global identification (CGI) of the remoteradio head such that the unique PRS is different from a PRS of the macroeNodeB, the PRS of the macro eNodeB being based on the PCI; and programcode to transmit the unique PRS.
 10. The computer program product ofclaim 9, further comprising program code to signal to a user equipment(UE) that the PRS is based on at least one of the cell globalidentification or the virtual cell ID.
 11. The computer program productof claim 9, further comprising program code to signal to a userequipment (UE), a position reference signal configuration of a pluralityof remote radio heads in neighboring cells when the UE is near a servingcell boundary.
 12. The computer program product of claim 9, furthercomprising: program code to receive uplink transmissions from a userequipment (UE); and program code to determine a position location of theUE based on the received uplink transmissions.
 13. An apparatus forwireless communication, comprising: means for generating a uniqueposition reference signal (PRS) for a remote radio head (RRH) having asame physical cell identity (PCI) as a macro eNodeB, the unique PRSbeing based on at least one of a virtual cell ID or unique cell globalidentification (CGI) of the remote radio head such that the unique PRSis different from a PRS of the macro eNodeB, the PRS of the macro eNodeBbeing based on the PCI; and means for transmitting the unique PRS. 14.The apparatus of claim 13, further comprising means for signaling to auser equipment (UE) that the PRS is based on at least one of the cellglobal identification or the virtual cell ID.
 15. The apparatus of claim13, further comprising means for signaling to a user equipment (UE), aposition reference signal configuration of a plurality of remote radioheads in neighboring cells when the UE is near a serving cell boundary.16. The apparatus of claim 13, further comprising: means for receivinguplink transmissions from a user equipment (UE); and means fordetermining a position location of the UE based on the received uplinktransmissions.